The demand for aromatic rice has increased in the United States during the last two decades. Jazzman, the first US-bred jasmine-type rice variety, was released by the Louisiana State University (LSU) AgCenter Rice Research Station in 2008 to compete for a market share of jasmine-type rice. Jazzman, a long grain aromatic rice variety, was developed from a cross between Ahrent and an unreleased aromatic Chinese rice line 96a-8. In pre-release field tests and laboratory scale evaluation, Jazzman rice yield and milling quality compared favorably with two high-yielding and good-milling non-aromatic long grain varieties, Cypress and Cheniere. Pilot scale evaluation of Jazzman for milling quality supported laboratory scale evaluation while providing additional data for milling optimization. Pilot scale milling uses larger rice samples than laboratory scale testing and employs a continuous process instead of the batch process used at laboratory scale. As a result, pilot scale milling offers more comprehensive information regarding the milling yield and quality of rice varieties as they are considered for industrial scale release. Another consideration for new rice varieties involves their potential for value-added processing, in which waste streams during processing can be used to create valuable products. The oil from rice bran is one such product. The objective of this study was to use pilot scale milling to determine the potential of Jazzman for industrial scale release, including its potential for value-added processing. Results showed that bran was easily removed during milling; the head rice recovery ranged from 66% to 74% as a function of milling flow rate. Water polishing had little effect on head rice recovery, but improved the final degree of milling (DOM) to a commercially acceptable level of 87 - 90. Additionally, rice bran oil concentration decreased as pilot scale flow rate increased, indicating that oil was concentrated in the outer bran layer of Jazzman. Pilot scale milling shows that Jazzman is a high-yielding and good-milling aromatic long grain rice variety.
The US demand for jasmine-type rice has increased over the last two decades. Most of this demand is currently met with imports [
Jazzman is a long grain aromatic rice variety that was developed from a cross between an Arkansas variety, Ahrent, and an unreleased aromatic Chinese rice line 96a-8. Jazzman averaged 7803 kg∙ha−1 in yield trials over five years in five states, comparing satisfactorily with two non-aromatic long grain varieties, Cypress and Cheniere [
Laboratory scale evaluation has traditionally provided milling quality information on new rice variety releases, and in most cases, successfully predicted industrial scale performance [
To provide a closer analog to commercial mills, the LSU AgCenter pilot scale mill was used to measure the milling performance of Jazzman. The LSU AgCenter pilot scale mill operates in a continuous process and requires a larger sample (at least 11.5 kg) than laboratory scale testing; this approach provides a similar operating process to the industrial scale and the larger sample size is thought to minimize errors due to orders of magnitude in scale up [
Milling quality assessment for rice varieties includes quantification of grain appearance and measurement of milling yield and head rice recovery. Grain appearance was measured using standard industry values of whiteness, transparency, and degree of milling (DOM) [
Despite its advantages to traditional laboratory scale milling, pilot scale milling has not been widely used in the development of new rice varieties. Thus, this study adds to the dearth of literature on this novel milling method. Hua et al. [
Pilot scale milling can also be used to assess the potential of a rice variety for value-added processing, a method in which waste streams produced during processing can be used to create other valuable products. Rice bran is a primary source of interest for value-added processing in rice milling. As world energy consumption increases, the United States Department of Energy (DOE) plans to replace fossil fuels with biofuels produced from biomass. Rice bran conforms to the DOE’s definition of biomass, which includes agricultural and forest residue, municipal solid waste, and energy crops [
Oil extracted from rice bran has been converted to biodiesel by a variety of methods including basic [
This study was motivated by collaboration between the Rice Research Station and the authors to provide additional milling information on this new rice variety and to provide pilot scale data for this rice variety for researchers who wish to further investigate this novel processing scale. Additionally, the byproduct of this rice variety could be used to produce biodiesel fuel. The objectives of this study were to:
1) Measure the percent of bran removed from Jazzman as a function of pilot scale milling flow rate;
2) Determine head rice recovery, whiteness, transparency, and DOM of Jazzman at these flow rates;
3) Identify the optimal range of pilot scale mill settings for Jazzman;
4) Determine the rice bran oil concentration as a function of pilot scale mill setting.
Jazzman rice was milled at the pilot scale at low, medium, and high flow rates in triplicate, and milling and quality parameters were determined. Rice bran obtained from these experiments was extracted and oil concentration was measured. The standard methods for experiments and analysis are detailed in the following paragraphs.
Jazzman provided by the LSU AgCenter Rice Research Station was stored in a freezer at 0˚C until the day before processing. A period of 24 hours allowed the rice to achieve ambient temperature at 29˚C before milling.
Rice was processed using a pilot scale milling plant (Satake Engineering Co. Tokyo, Japan) which operates in a continuous process and consists of a husker (model GPS300A), a mill (model VAF10AM), a wet polisher (model BA3AW), and a color sorter (model GS3AA). Samples of 11.5 kg were processed in triplicate at three selected pilot scale operational settings corresponding to low, medium, and high flow rates of milling. Milled rice refers to rice that has been processed with the milling or whitening unit (model VAF10AM), while polished rice refers to rice that has been further processed through the water polisher (model BA3AW).
The pilot scale mill has flow settings ranging from 1 to 9. These settings correspond to mass flow rates that are specific for a given rice variety, and range from approximately 50 kg∙h−1 at flow setting 1 to approximately 850 kg∙h−1 at flow setting 9. These values are approximate because different rice varieties will have different mass flow rates as a function of how difficult the bran is to remove from the kernel. Thus, the flow rate of rice of a particular rice variety is determined for a specific flow setting by measuring the mass of a given volume of rice (11.5 kg) that leaves the whitening unit divided by the time it takes for that rice to pass through the chamber. From triplicate measurements, mean flow rates were reported in kg∙h−1 for pilot scale mill settings of 3, 5, and 9. The actual mean flow rates in kg∙h−1 for the three settings used were 124, 344, and 806, respectively. The selected settings corresponded to the low, medium, and high flow rates, respectively, determined in previous optimization studies of rice milling, which showed that flow rate setting was the controlling factor in pilot scale milling [
Nine rough rice samples of 11.5 kg were shelled, milled, and their weights measured after each process step. Shelled rice samples of 125 g and 2.5 kg were collected from each replicate processed. The 2.5 kg sample was further processed through the water polisher and reweighed. From the polished rice, samples of 125 g were collected. A shaker table (Model 61-115-60, Grainman Machinery Co., Miami, Florida) using sorter trays of ASTM size 10 (top) and 12 (bottom) removed broken kernels of rice from the 125 g milled and polished rice samples. Head rice recovery was determined as a weight percent of unbroken kernels to the weight of the rough rice sample processed for milled and polished rice [
Rice bran samples were collected from each replicate and rice bran oil was extracted using the method detailed in Proctor et al. [
Experiments were completely randomized. Three replicates were performed for each milling flow rate combination. Statistical analysis at a 5% significance level was performed with ANOVA and Tukey mean comparisons using XLSTAT-Pro 2009 [
Jazzman milling yield and head rice recovery compare well to non-aromatic and aromatic long grain rice varieties. Head rice recovery decreased with increasing flow rate for milled and polished Jazzman due to the increase in friction milling at higher flow rates. No significant difference existed between mean values for milled and polished head rice recovery, which were 70.9% and 70.8% respectively. Laboratory scale evaluation found a head rice recovery of 63.6%. Jazzman head rice recovery compares well with head rice recovery values of Cypress and Cheniere, which are considered good milling varieties of rice with head rice recovery values of 64.3% and 63.4%, respectively [
The mean pilot scale head rice recovery value of 71% was higher than the laboratory measurement of 63.6%. This is likely due to the batch lab versus continuous pilot scale differences in processing. Laboratory scale mills operate in a batch format with all milling accomplished in one step. Pilot scale mills operate by removing bran
Rice milling and quality measurements | Milling flow rate, kg.h−1 | |||
---|---|---|---|---|
Quality of rice | 124 | 344 | 806 | |
Bran removed (%) | Milled rice | 12.2 ± 2.0a | 13.0 ± 3.1a | 13.6 ± 2.9a |
Polished rice | 3.4 ± 1.0a | 1.0 ± 0.3b | 0.6 ± 0.5b | |
Head rice recovery (%) | Milled rice | 74 ± 0.5a | 72 ± 1.4a | 66 ± 1.2b |
Polished rice | 73 ± 1.6a | 70 ± 3.3a | 69 ± 0.0b | |
Degree of milling (DOM) | Milled rice | 73 ± 4.9a* | 80 ± 3.0a | 86 ± 2.1b |
Polished rice | 87 ± 7.8a* | 88 ± 5.3a | 90 ± 4.0a | |
Whiteness | Milled rice | 33.5 ± 0.8a* | 35.6 ± 0.7a | 37.0 ± 0.4b |
Polished rice | 37.4 ±1.5a* | 37.1 ± 1.1a | 38.0 ± 1.1a | |
Transparency | Milled rice | 3.7 ± 0.2a* | 3.5 ± 0.1a | 3.4 ± 0.1b |
Polished rice | 3.2 ± 0.2a | 3.6 ± 0.2a | 3.4 ± 0.2a |
Values ± 1 standard deviation reported. The same letter across a row indicates no statistical difference; * indicates two data points.
in a series of steps. Chen et al. [
Mean milling yield is 90% for Jazzman, which compares well with Cypress, Cheniere, and Cocodrie yields of 91%, 87%, and 88%, respectively [
Measurements for DOM, whiteness, and transparency indicate the visual quality of rice kernels. There is a lack of data regarding published values of whiteness and transparency [
DOM ranges from 85 to 95 [
For milled rice, Jazzman exhibited minimal differences in head rice recovery and DOM among flow rates.
Head rice recovery for a flow rate of 806 kg∙h−1 was lower than for flow rates of 124 and 344 kg∙h−1. Head rice recovery values at flow rates of 124 and 344 kg∙h−1 exhibited no statistical difference. Milled rice DOM values exhibited no difference between 344 and 806 kg∙h−1. The data indicate that low flow rate milling optimizes head rice recovery and DOM. Milled rice at 124 kg/hr has a head rice recovery of 74 and a DOM of 73. The head rice recovery exceeded values for Cypress and Cheniere with head rice recoveries of 64 and 63, respectively. The DOM value for milled rice fails to meet industry expectations for DOM of 85 to 95 [
Pilot scale milling results suggest that the Jazzman rice variety can be scaled up to industrial levels with acceptable kernel quality and milling yields that meet or exceed that of current commercial varieties. The product obtained would be able to compete well with other long grain aromatic rice varieties for the niche aromatic rice market in the United States. More broadly, this study illustrates the impact of pilot scale milling in new rice variety development. Milling at pilot scale is improved over milling at lab scale as it more closely mirrors industrial scale milling. This study showed that for this particular variety, the mean head rice recovery (71%) was significantly higher than the value obtained at laboratory scale (63%). Such differences can “make or break” a prospective rice variety, and conditions that more closely model the actual industrial scale process provide millers with a better data set from which to judge commercial viability. Industrial scale millers can use pilot scale milling data, such as the data presented in this paper, to determine initial mill settings for a new rice variety and can fine tune milling by adjusting their milling ratios to maximize milling and/or quality parameters. Researchers focused on rice variety development can use pilot scale milling data to drive rice variety development and/or improvement. For example, the LSU AgCenter rice research station released Jazzman 2 [
Schramm et al. [
Jazzman presented as a high-yield, commercially viable milling aromatic rice variety. Yield and milling quality were comparable to two commercially successful non-aromatic varieties grown in the same area and to two long grain aromatic varieties grown in Bangladesh. Pilot scale milling of Jazzman showed that bran was removed easily from this variety and that rice milling at low flow rate with subsequent water polishing maximized yield, produced kernels of commercially acceptable quality, and produced rice bran with the highest percent oil that could be extracted for use in applications such as production of biodiesel. Pilot scale milling can be important to screen new rice varieties for their commercial viability and potential for value-added processing.
Future studies can test more rice varieties as a function of milling scale (laboratory, pilot, and/or industrial) to determine if models can be developed to accurately predict the milling yield and quality of a prospective rice variety based on laboratory or pilot scale milling data.
The authors gratefully acknowledge Steve Linscombe and the LSU AgCenter Rice Research Station for providing the rice milled for this study and the on-going collaboration that produced this research. LSU and the LSU AgCenter provided financial support for this research.
RebeccaSchramm,GrantGonzalez,NicoleWalker,MarybethLima, (2015) Pilot Scale Mill Characterization and Evaluation of Rice Bran Oil Concentration of Jazzman Rice. American Journal of Plant Sciences,06,1885-1892. doi: 10.4236/ajps.2015.612189